Jenna McMurray and Damien Wood, QMI Agency

CALGARY - Police have not found a missing five-year-old Calgary boy and his grandparents, but they are talking to a person of interest in the case.

In a press conference Saturday evening, police confirmed an investigation on a rural property near Airdrie, north of Calgary, was related to the case.

Officers were conducting grid searches of the property Saturday and were also seraching by air. During a press conference, Insp. Joel Matthews offered few details about what they were looking for, but said officers were hoping to spot “anything that would help us solve this file and find this family.”

Police began searching the area after receiving a tip a green truck they were looking for was located on the property.

Matthews said it is not yet confirmed the vehicle is the one they’re looking for, and at this point the man is only in custody to be questioned.

He was not combative with police, Matthews said.

Matthews called the scouring of the property the latest investigative step.

“It may not lead where we want it to lead,” he said.

On the hope of finding the missing trio alive, he said investigators were “still searching, still investigating.”

“We don’t know one way or the other.”

Five-year-old Nathan O’Brien and his grandparents, Alvin and Kathy Liknes, went missing sometime between 10 p.m. Sunday night and 10 a.m. Monday morning. O’Brien was sleeping over at his grandparents’ place after an estate sale at their home.

They were reported missing after Jen O’Brien, Nathan’s mother, arrived at the home to pick him up and found it empty.

An Amber Alert remained in effect Saturday evening.

A driveway to the property near Airdrie was blocked off by several police vehicles, including a Special Tactical Operations truck, while signs on the road alerted drivers that police operations were in progress.

Leo Velasco, a neighbour who lives a few properties down, said he saw several police vehicles drive down the road Friday and added he also spotted a helicopter circling the area.

Out walking his dog Saturday afternoon, he said it was surreal to see the scene, as it’s a very quiet rural area.

Earlier in the day about 20 uniformed officers plus up to 50 Search and Rescue personnel were searching a 400-metre area around the Liknes home.

“It’s basically to see if we’ve missed anything, we can see if there’s anything we haven’t picked up,” Sgt. Daniela Seravalli with Calgary Police said.

Police said Friday there was evidence a “violent crime” had occurred in the Liknes home.